In the raising of poultry it is common to use elongated watering troughs which are fed by automatic water feed valves. Generally a watering trough for poultry will be an elongated channel pivotally attached at one end to a wall or other rigid support and having a second end attached to a control lever for an automatic valve. The valve attached to the control lever is responsive to the weight of the water in the trough and will automatically replenish the supply as it is lost through drinking by the poultry or evaporation into the air. When a sufficient amount of water is in the trough, the weight of the trough as applied to the control lever of the valve will cause the valve to shut off the supply of water.
As is known to those skilled in the art, it is also desirable to have the control valve cut off to flow when the trough is removed so that removal of the trough will not cause water to be spilled onto the floor of the poultry house.
The general arrangement for valves for poultry watering troughs is well known in the art. For example, U.S. Pat. No. 2,800,917 to Hoffmeister, U.S. Pat. No. 2,634,755 to Hobbs, and U.S. Pat. No. 3,090,399 to Godshalk all show species of control valve for poultry watering apparatus. The valves described in these patents all include a spring biased lever which will bias a valve operating mechanism shut when the weight of the water trough is removed from the control lever. Each of the biasing springs may be adjusted to control the total force applied by the watering trough which will shut off the valve when the lever is urged downward by the weight of the trough and the water.
Prior art water control valves of the type shown in the above-referenced patents all include a pair of weighted members attached to each other by a pin passing through a bore in the interior of the valve housing. The pin is longer than the length of the bore. Therefore the basic arrangement takes on the appearance of a barbell having the bar passing through a bored out portion in the interior of the valve housing. On both the upper and lower sides of the bore a valve seat is provided so that when the upper weight is seated on top of the bore, flow of water through the valve housing is terminated. Similarly when the lower weight is urged upward against the lower valve seat, the water flow is also terminated.
When the force urging the weights upward which comes from the weight of the trough at a support location working against the spring bias on a lever arm is substantially cancelled by the force of the water pressure in a feed line, neither weight will be seated in one of the valve seats and water will flow through the valve.
There are two main disadvantages to prior art watering valves of the type described above. The first disadvantage is that construction of such valves requires a relatively large number of machined metal parts, particularly the valve seats and the arrangement of weights and the pin or bar passing through the bore running between the seats.
The second main disadvantage of prior art watering valves, as will be appreciated from inspection of the above-referenced patents, is that it is relatively common for particulate matter to collect between the walls of the bore and the pin joining the valve weights which tends to clog the valve and prevent its proper operation. Adequate cleaning of a valve so clogged generally requires the removal thereof and a somewhat tedious cleaning process. It may require disassembly of the valve.